1. Technical Field Disclosure
The present disclosure relates to a light device with light emitting diodes. More particularly, the present disclosure relates to a light device with red and blue light emitting diodes.
2. Description of Related Art
As one of the important light devices, white light emitting diodes (LEDs) are gradually applied in a wide variety of lighting equipments and the back light sources of the liquid crystal displays (LCDs) because of the advantages such as power saving, low driven voltages, long life time, and being environment-friendly. A white light with high color rendering index (CRI) is always a main goal of developing the semiconductor light sources.
There are some familiar methods to produce white light emitting diodes in the prior art. The first method uses different color diode chips with multiple wavelengths, e.g., red, blue and green chips, as light sources to make white light. However, there are some problems such as reaching only CRI of 80, and the non-uniformity mixed light for the light sources. Secondly, monochromatic blue light emitting element incorporated with yellow phosphor materials is applied for generating the white light. Although the white light therefore generated has high illumination efficiency, the low CRI and limited color saturation lead to the low efficiency in color mixture. In addition, it is observed that the chromaticity overly shifts in the chart under high electrical current. The third method uses phosphors excited by ultra-violet (UV) light to generate the white light. Since there still are unsolved deteriorating problems of applying the UV light in LED, it is hard to precisely control the illumination efficiency and luminescence characteristics. The problem of low illumination efficiency for the UV light emitting LEDs needs to improve the quality of epitaxy.
As a result, there are still some inconveniences and disadvantages in the real operations of the foregoing familiar production methods of the white light emitting diodes.